The objective of the proposed research is to provide information about the determinants and functions of problem solving in late adulthood. Middle-aged and elderly persons would be tested on a series of Piagetian tasks. Analyses would focus on patterns of concrete- and formal-operational thought for individual adults. Performance would be examined as a function of health status, initial education, and age, and the effects of task familiarity would be assessed. Interview techniques would be used to identify instances of concrete and formal thought in everyday adult life. The information provided by this research would help to expand current conceptualizations of adult cognition and could potentially be used in predicting the performance of older adults in educational and vocational training pursuits.